1. Field of the Invention
The present invention relates to a light emitting apparatus.
2. Description of the Related Art
In recent years, high power and light emission efficiency improvement are required for light emitting apparatuses that include a semiconductor light emitting device. For this reason, a current is increased that is applied to the device. Also, the number of the semiconductor light emitting devices is increased. Also, the light emission area of the semiconductor light emitting device is increased. These measurements are made to increase the light power of light source itself. Also, a light emitting apparatus has been developed that eliminates factors of optical loss to increase the light outgoing amount of the light emitting apparatus as a whole (for example, Japanese Patent Laid-Open Publication No. 2006-93697). With reference to FIGS. 31-33, an exemplary light emitting apparatus is shown that has structure capable of suppressing absorption of light emitted from a light source by an electrostatic discharge shock protection device. FIG. 31 is a cross-sectional view showing a light emitting apparatus 100 that includes a plurality of semiconductor light emitting devices 104. FIG. 32 is a cross-sectional view showing the light emitting apparatus 100 taken along the line XXXII-XXXII′ in FIG. 31. FIG. 33 is a cross-sectional view of the light emitting apparatus 100 taken along the line XXXIII-XXXIII′ line in FIG. 31.
As shown in FIGS. 31 and 32, the light emitting apparatus 100 includes a lead frame 103 that includes a pair of cathode lead 101 and anode leads 102 that are spaced away from each other. The plurality of semiconductor light emitting devices 104 are mounted on the cathode lead 101. An electrostatic discharge shock protection element 105 is mounted on the anode lead 102. As shown in FIGS. 31 and 33, a recessed area forming portion 106 covers most part of the lead frame 103 except the semiconductor light emitting devices 104, and forms recessed areas by wall surfaces of the recessed area forming portion 106 that surround the peripheries of the device 104. That is, the semiconductor light emitting device 104 is mounted on the bottom surface of the interior of each of the recessed areas that opens in a generally stepped shape. The electrostatic discharge shock protection device 105 is embedded in a wall of the recessed area forming portion 106. The recessed area forming portion 106 is formed of a white TiO2 group thermosetting resin material by molding. SiO2 glass fills the recessed areas of the recessed area forming portion 106.
In the case of the thus-configured light emitting apparatus 100, since the electrostatic discharge shock protection device 105 is embedded in the recessed area forming portion 106, the electrostatic discharge shock protection device 105 is not externally exposed. For this reason, light emitted from the semiconductor light emitting device 104 does not travel to the electrostatic discharge shock protection device 105. Accordingly, it can be prevented that the outgoing light is partially absorbed by the electrostatic discharge shock protection device 105. Also, it can be suppressed that the emitted light is reflected by the electrostatic discharge shock protection device 105, and that the light travels in an undesired direction. As a result, it is possible to increase the light outgoing efficiency of the apparatus as a whole, and to provide a light emitting apparatus with high illumination.
However, in recent years, the output of light emitting device is remarkably increased. In particular, in a light emitting apparatus that includes a light emitting device capable of emitting short wavelength light or blue group light, as the output of light emitting device is further increased, heat is getting increased that is generated from a wavelength conversion member that can convert the wavelength or an excitation light source, or the light source itself. This may cause problem in that the characteristic of device deteriorates. In addition to this, this may cause a crack of a member or the like, and may reduce the reliability of apparatus. As shown in particular in FIG. 31, in the case of the apparatus that is configured to mount a plurality of devices only one of anode and cathode leads, the heat amount in the apparatus is likely to be unevenly distributed. In this case, if heat is not sufficiently dispersed from and is stored in a member, the member is subjected to stress caused by the difference of the thermal expansion coefficients between parts. In particular, stress is likely to occur on the boundary between different members. For this reason, a crack is likely to appear on the boundary. Accordingly, in the light emitting apparatus that is configured to form the recessed area forming portion that is formed of resin by molding and holds a member that is formed of a material different from the recessed area forming portion and is embed in the recessed area forming portion as shown in FIG. 31, there is a problem in that a crack is likely to appear on the boundary between the members formed of different materials. In addition to this, for the increase of light amount, the recessed area forming portion is required to be improved in light resistance and heat resistance.